ABSORPTION BY ROOTS

Detailed Study:


Brief Revision:

https://www.youtube.com/watch?v=8Vt9hkZLq24&list=PLhf4hr_x5XyQWQNFIfhh589X9WCqEf1J4&index=3

Frequently Tested Topics:

  • Diffusion

  • Osmosis, Endosmosis, Exosmosis

  • Experiments on Osmosis

  • Tonicity

  • Active Transport

  • Turgidity, Flaccidity, Plasmolysis

  • Conduction of Water in Root Hair

*Note that other aspects of the chapter are equally important.

Important Diagrams:

  • Structure of Root Hair

  • Experiment Demonstrating Osmosis

  • Turgid, Flaccid, and Plasmolysed Cells

  • Conduction of Water in a Root Hair and Xylem Vessels

Important Past Questions:

  • Name the following:

i) The process by which root hairs absorb water from the soil. (2017)

ii) The process of uptake of mineral ions against the concentration gradient using energy from the cell. (2015)

  • Explain the following term:

 Diffusion.

(2010)

  • Correct the following statement by changing the underlined words.

i) The cell sap of root hair is hypotonic. (2018)

ii) Free movement of solutes in and out of the cell takes place across the cell membrane. (2017)

  • Differentiate between the following on the basis of what is given in the brackets:

Hypotonic solution and Hypertonic solution (condition of a plant cell when placed in them)

(2018)

  • Account for the following:

Wilted lettuce leaves become crisp/firm when placed in cold water for a while.

(2010)

  • ____________ is the phenomenon of contraction of the cytoplasm from the cell wall. 

(2011)

  • Give biological terms for the following: 

Movement of  molecules of a substance from their higher concentration to lower concentration when they are in direct contact. 

(2018)

DIAGRAM BASED QUESTIONS

The figure given below is a diagrammatic representation of a part of the cross section of the root in the root hair zone. Study the same and then answer the question that follow:
i) Name the parts indicated by the guidelines 1 to 4. 
ii) Which is the process that enables the passage of water from the soil into the root hair ?
iii) Name the pressure that is responsible for the movement of water in the direction indicated by the arrows. Define it. 
iv) Due to an excess of this pressure sometimes drops of water are found along the leaf margins of some plants especially in the early mornings. What is the phenomenon called ? 
v) Draw a well labelled diagram of the root hair cell as it would appear d an excess of fertilizer is added to the soil close to it. 
(2016)

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The diagram below represents a layer of epidermal cells showing a fully-grown root hair. Study the diagram and answer the questions that follow:
i) Name the parts labelled A, B, C, D. 
ii) The root hair cell is in turgid state. Name and explain the process that caused its state.
iii) Mention one distinct difference between the parts labelled A and B.
iv) Draw a diagram of the above root hair as it would appear when a concentrated solution of fertilizers is added near it.
(2011)

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Given below is the diagram of an apparatus set up to study a very important physiological process :
i) Name the process being studied.
ii) Explain the process.
iii) What change would you observe in the thistle funnel containing sugar solution after about 10 minutes ?
iv) Is sugar solution hypertonic or hypotonic ?
v) Name the part of the plant cell which is represented by the sugar solution.
vi) Explain why much salt is added to pickles.
(2010)

The figure given below shows the epidermal cells of an onion bulb. This cell was then transferred to a drop of sugar solution.
i) Draw a well labelled diagram of the epidermal cells as it would appear after immersion in a strong sugar solution.
ii) What scientific term is used for the changes as shown in (i) above?
iii) What should be done to restore the cell back to its original condition?
iv) Give the scientific term for the recovery of the cell as a result of the step taken in (iii) above.
v) Define the term osmosis.

(2013)

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